The cellular network is a communication system that interconnects billions of Mobile Devices to one another and, in turn, to the Internet. The Internet is a communication system that provides connectivity to billions of users with laptops, notebooks, desktops, Internet Enabled TV sets, and mobile devices coupled to the Internet either through the cellular network or via other types of wireless connectivity standards such as cellular, Wi-Fi. Bluetooth, and WiMAX mobile devices. A set of standards for cellular phones includes, for example, 1G, 2G, 3G, 4G LTE, 4G, and 5G which are used by mobile devices to send and receive data, video or voice. The G stands for Generation and LTE stands for Long-Term Evolution. Cellular, Wi-Fi, Bluetooth, and WiMAX standards may be used in cellular phones, smartphones like the iPhone™, Android™, Windows™, and Blackberry™, tablets, and wearable devices.
In recent years, Mobile Devices have been provided with means to determine their position at any given time, The terms position and location are used interchangeably in this document. Once determined, the position of a Mobile Device can be used to enable Location-Based Services, which uses location as the control feature to customize a certain service, and a wide variety of Location-Based Mobile Applications. Examples of Location-Based Mobile Applications include navigation applications, tracking applications, and applications that provide content to the user that is related to the current position of the Mobile Device (e.g., provide a user using a Mobile Application in a certain store with an offer from that store, or provide a user using a Mobile Application in a neighborhood with information on nearby businesses and attractions).
FIG. 1A illustrates that the position of a Mobile Device 1-1 can be determined as an absolute position or a relative position. FIG. 1A shows the Mobile Device Absolute Position 1-2, which is a geographic position expressed in the geographic coordinates Mobile Device Longitude 1-3 and Mobile Device Latitude 1-4. Mobile Device Longitude 1-3 specifies the east-west position and Mobile Device Latitude 1-4 specifies the north-south position of the Mobile Device 1-1 on the Earth's surface. The Mobile Device Longitude 1-3 is expressed as an angle east or west from the Prime Meridian, which is the Meridian that passes through the Royal Observatory, Greenwich. The Mobile Device Latitude 1-4 is expressed as an angle that ranges from 0° at the Equator to 90° North at the North Pole and to 90° South at the South Pole.
A relative position is a position relative to a Reference Point. FIG. 1B illustrates a first method to define a relative position of a Mobile Device 1-1 using a Relative Cartesian Coordinate System 1-5. The Relative Cartesian Coordinate System 1-5 specifies the Mobile Device Relative Position 1-12 in a plane by a pair of numerical coordinates Mobile Device Relative X-Coordinate 1-13 and Mobile Device Relative Y-Coordinate 1-14, which are the signed distances from the Mobile Device 1-1 to two fixed perpendicular reference lines, one called the X Axis 1-10 and one called the Y Axis 1-11. The point where they meet is called the origin. By making the origin coincide with the Reference Point 1-6, and making the X Axis 1-10 parallel to the east-west direction (and therefore the Y axis 1-11 parallel to the north-south direction), the Mobile Device Absolute Position 1-2 can be computed from the Reference Point Absolute Position 1-7, which is defined by the Reference Point Longitude 1-8 and Reference Point Latitude 1-9, using the Mobile Device Relative X-Coordinate 1-13 and the Mobile Device Relative Y-Coordinate 1-14.
FIG. 1C illustrates a second method to define a relative position of a Mobile Device 1-1 using a Relative Polar Coordinate System 1-15. The Relative Polar Coordinate System 1-15 specifies the Mobile Device Relative Position 1-12 in as plane by a pair of coordinates, a first coordinate called Mobile Device Relative Radial Coordinate 1-16, which is the distance from the Mobile Device 1-1 to the Reference Point 1-6, and a second coordinate called Mobile Device Relative Angular Coordinate 1-17, which is the angle of the radius from the Mobile Device 1-1 to the Reference Point 1-6 and the X-Axis 1-10. The Mobile Device Absolute Position 1-2 can be computed from the Reference Point Absolute Position 1-7, which is defined by the Reference Point Longitude 1-8 and Reference Point Latitude 1-9, using the Mobile Device Relative Radial Coordinate 1-16 and Mobile Device Relative Angular Coordinate 1-17.
All the examples above illustrate ways to define the absolute and relative positions in a two-dimensional space, but an expert in the art would know how to extend similar concepts to define the absolute and relative position of a Mobile Device 1-1 in a three-dimensional space, by adding an altitude for the Mobile Device Absolute Position 1-2, a Z Axis and Z-Coordinate for the Relative Cartesian Coordinate System 1-5, and a second Relative Angular Coordinate :for the Relative Polar Coordinate System 1-15.
The absolute or relative position of a Mobile Device can be determined using a positioning system. We use the terms positioning system, positioning mechanism, and positioning method interchangeably. Examples of positioning systems include the Global Positioning System (GPS), the Differential GPS, the Assisted GPS, several types of Wi-Fi Based Positioning Systems, and other positioning systems. A positioning system determines the position of a Mobile Device by performing a position computation using a variety of different mechanisms. A positioning system determines the position of a Mobile Device with a certain positioning accuracy, meaning that the position computation contains a certain error, which is introduced by a number of factors that play a role in the computation. The accuracy of a positioning system depends on the mechanisms that the positioning system uses to perform the position computation and on the position itself. Certain positions can be computed with lower or higher accuracy than other positions, depending on a variety of factors. The positioning error means that the actual absolute or relative position of a Mobile Device is only known with a certain uncertainty. This uncertainty can be thought as a region surrounding the actual position of the Mobile Device, and the Mobile Device can be positioned anywhere within that region. Several mechanisms are used to minimize the positioning error. A Location-Based Mobile Application may have certain requirements in terms of the positioning accuracy that is needed for the Location-Based Mobile Application to work properly. For example, a navigational Mobile Application may work properly with an accuracy of several meters, while a tracking Mobile Application that needs to determine which exact product in a supermarket aisle a consumer is facing at a given time may work properly only if the accuracy is about one meter.
FIG. 2A illustrates the Global Positioning System (GPS) 2-1, which consists of a plurality of GPS satellites, comprising GPS Satellite 1 2-2 to GPS Satellite N 2-3. The Global Positioning System (GPS) 2-1 is a space-based satellite navigation system that provides location and time information in all weather conditions to a Mobile Device 1-1 containing a GPS receiver 2-4 anywhere on the Earth where there is an unobstructed line of sight to four or more GPS satellites. As of December 2012, there were 32 GPS satellites in the Global Positioning System 2-1. GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. The GPS receiver 2-4 uses the messages it receives from the satellites to determine the transit time of each message and computes the distance to each satellite. Then, the computed distances are used to compute the location of the GPS receiver 2-4 using triangulation. The location of the GPS receiver provides the Mobile Device Absolute Position 1-2 in terms of the Mobile Device Longitude 1-3 and Mobile Device Latitude 1-4. About nine satellites are visible from many locations on the ground at any one time. The additional satellites improve the precision of GPS receiver calculation by providing redundant measurements. However, buildings, vegetation, and other obstructions may make one or more satellites not visible from a certain location. When the GPS receiver 2-4 is first turned on, it needs to find orbit and clock data for the relevant satellites. The procedure of acquiring the signal may take time, even of the order of a minute or more, before the location can be computed. This time is called Time to First Fix, and depends on the location, since obstructions and other interferences can make more difficult for the GPS receiver 2-4 to acquire a signal.
The GPS receiver 2-4 computes the Mobile Device Absolute Position 1-2 with a certain accuracy. Several errors may be introduced in the calculation, which affect the precision of the computed location. For example, the GPS receiver 2-4 computes the distance to each GPS satellite in the plurality of GPS Satellites 2-2 to 2-3 by multiplying a signal's travel time by the speed of light. However, the speed of light is not constant as the signal travels through the ionosphere and the troposphere, and thus this calculation introduces an error. Other examples of errors include the multipath errors, the ephemeris errors, the receiver noise error, and errors in the satellite's clock. The GPS receiver 2-4 may include means to correct, at least in part, one or more of these errors. The accuracy of the GPS receiver 2-4 depends on the GPS receiver 2-4 and on the number and position of GPS satellites visible at any given time from a certain position. The accuracy of the GPS calculation depends therefore on the location and time. On average, most GPS receivers have an accuracy of a few tens of meters. The accuracy of the OPS receiver 2-4 rapidly decreases (and eventually the GPS location calculation cannot be performed) if the GPS receiver 2-4 is indoor or if there are any other impediments to its line of sight to the satellites.
A first method to improve the accuracy of the GPS is Differential GPS (DGPS), which is also shown in FIG. 2A, DGPS comprises a network of fixed, around-based DGPS Reference Stations, comprising DGPS Reference Station 1 2-5 to DGPS Reference Station N 2-6, which broadcast the difference between the positions indicated by the GPS satellites and the known fixed positions of each DGPS Reference Station. The difference correction signal is broadcast to DGPS-capable GPS receivers using ground-based transmitters to improve the accuracy of the computation. A second method to improve the accuracy of GPS is called Wide-Area Augmentation System (WAAS). WAAS is conceptually similar to DGPS. WAAS is a system of 25 ground WAAS Reference Stations positioned across the United States that monitor GPS satellite data and create GPS correction messages which can be received by WAAS-enabled GPS receivers to improve the accuracy of the computation. On average, the accuracy of WAAS-enabled GPS receivers is about 3 meters.
FIG. 2B illustrates a Mobile Device 1-1, such as a cellphone, a smartphone, a tablet, or a wearable device, connected to the Cellular Network 2-7, which is in turn connected to the Internet 2-8. The Mobile Device 1-1 connects to the Cellular Network 2-7 via a plurality of Cell Towers comprising Cell Tower 1 2-9 to Cell Tower N 2-10 via radio signals. Each Cell Tower in the plurality of Cell Towers 2-9 to 240 includes a Base Station, which receives and transmits the radio signals to communicate with the Mobile Device 1-1. Most Mobile Devices such as smartphones and tablets include a GPS receiver 2-4 capable of receiving messages from the Global Positioning System 2-1 and compute the Mobile Device Absolute Position 1-2.
Most Mobile Devices such as cellphones, smartphones, tablets, and other devices that are attached to the Cellular Network 2-7 use Assisted Global Positioning System (Assisted GPS) rather than the basic GPS described above to compute the Mobile Device Absolute Position 1-2. Assisted GPS takes advantage of the fact that the Mobile Device 1-1 is attached to the Cellular Network 2-7 to improve the performance of the GPS computation. Each Cell Tower in the plurality of Cell Towers 2-9 to 2-10 comprises a GPS receiver that collects GPS information from the GPS Satellites, at the known location of the Cell Tower. Assisted GPS uses an Assisted GPS Server 2-11, which collects the GPS information collected by the Cell Towers, processes it, and passes it to the Mobile Device 1-1 through radio signals to assist and improve the GPS computation of the Mobile Device Absolute Position 1-2. For example, the Assisted GPS Server 2-11 can compute which are the relevant GPS Satellites that a Mobile Device 1-1 attached to a specific Cell Tower should acquire, can generate correction messages on the GPS information, and can use additional information to help determine the Mobile Device Absolute Position 1-2.
Assisted GPS improves the performance of GPS computation in several ways. Assisted GPS improves the Time to First Fix, since the Assisted GPS Server 2-11 can provide the Mobile Device 1-1 with the list of relevant GPS Satellites that should be acquired. Part of the GPS computation can be performed in the Assisted GPS Server 2-11 rather than in the Mobile Device 1-1, which requires less processing power in the Mobile Device 1-1 and saves battery life. The Assisted GPS Server can also use additional positioning, methods to improve the accuracy of the GPS computation in non-optimal locations, such as when the Mobile Device 1-1 is indoors or in a location where the line of sight to the GPS Satellites is obstructed. In certain cases, using the Assisted GPS, the Mobile Device Absolute Position 1-2 may be computed even in locations where there is no line of sight to GPS Satellites, whereby the basic GPS may not be able to compute the location.
A positioning mechanism that the Assisted GPS Server 2-11 uses to improve the accuracy of the computation of the Mobile Device Absolute Position 1-2 when the location may not be optimal for GPS computation is Cell Tower triangulation. In most cases, a Mobile Device 1-1, which is attached to the Cellular Network 2-7 via the plurality of Cell Towers comprising Cell Tower 1 2-9 to Cell Tower N 2-10, actually communicates with more than one Cell Tower at any given time. At a given time, a Mobile Device 1-1 may be attached to a first Cell Tower 1 2-9 and a second Cell Tower N 240. Each Cell Tower can compute the Mobile Device Relative Position 1-12, relative to the Cell Tower itself, for example by estimating the distance of the Mobile Device 1-1 from the Cell Tower based on the travel time of the radio signal through the air, and the angle with which the radio signals from the Mobile Device 1-1 are received at the Cell Tower. Typically, the Mobile Device Relative Position 1-12 relative to a first Cell Tower 1 2-9 computed in this way is quite inaccurate. However, if the Mobile Device Relative Position 1-12 of a Mobile Device 1-1 which is attached to more than one Cell Tower is computed relative to more than one Cell Tower, then the computations can be combined by the Assisted GPS Server 2-11 using Cell Tower triangulation and the Mobile Device Absolute Position 1-2 can be computed with better accuracy. This information can in turn be combined with the result of GPS computation to further improve the accuracy of the computed Mobile Device Absolute Position 1-2.
FIG. 2C illustrates a similar positioning mechanism to Cell Tower triangulation that can be used to compute the Mobile Device Absolute Position 1-2 when the Mobile Device 1-1 is attached to the Internet 2-8 via Wi-Fi. This positioning mechanism is called Wi-Fi-Based Positioning, and is prevalently used indoors or in confined areas, such as in a stadium or a shopping mall. One example of Wi-Fi-based Positioning uses a plurality of Wi-Fi Hotspots comprising Wi-Fi Hotspot 1 2-13 to Wi-Fi Hotspot N 2-14. The Wi-Fi Hotspots may be connected to a Local Area Network 2-15, which in turn is connected to the Internet 2-8. The Mobile Device 1-1 includes a Wi-Fi radio that can connect to these Wi-Fi Hotspots. A Wi-Fi Position Server 2-16 computes the distance of the Mobile Device 1-1 to each Wi-Fi Hotspot, and computes the Mobile Device Absolute Position 1-2 or the Mobile Device Relative Position 1-12 using Wi-Fi Hotspot triangulation. The accuracy of the position computation depends on the number of Wi-Fi Hotspots covering a certain location and on the specific computation method used in the Wi-Fi Position Server 2-16.
The Assisted GPS using Cell Tower triangulation and the Wi-Fi-Based Positioning are examples of Hybrid Positioning Systems, illustrated in FIG. 3. A Hybrid Positioning System 3-1 uses more than one positioning mechanism to compute the Mobile Device Absolute Position 1-2. By using more than one positioning mechanism, better accuracy in the computation may be achieved, especially in locations where local conditions may be challenging for a specific positioning system. The Hybrid Positioning System 3-1 may compute a plurality of Position Data comprising a first Position Data 1 3-2 and a second Position Data 2 3-3, the first Position Data 1 3-2 computed using a first position computation mechanism and the second Position Data 2 3-3 computed using a second position computation mechanism. In the Combine 3-6 step, the Hybrid Positioning System 3-1 combines the first Position Data 1 3-2 and the second Position Data 2 3-3, and in the Compute 3-7 step it computes the Mobile Device Absolute Position 1-2. The Hybrid Positioning System 3-1 may use the first Position Data 1 3-2 and the second Position Data 2 3-2 in different ways to compute a more accurate Mobile Device Absolute Position 1-2.
In a first example, the Hybrid Positioning System 3-1 uses the plurality of Position Data as redundant measures, which improves the accuracy of the computed Mobile Device Absolute Position 1-2. For example, the first Position Data 1 3-2 yields a first estimate of the Mobile Device Absolute Position, together with a first Position Accuracy 3-4; the second Position Data 2 3-3 yields a second estimate of the Mobile Device Absolute Position, together with a second Position Accuracy 3-5. By combining the first estimate and the second estimate of the Mobile Device Absolute Position, a Mobile Device Absolute Position 1-2 is computed with better accuracy. In a second example, the Hybrid Positioning System 3-1 uses the second Position Data 2 3-3 to calibrate the first Position Data 1 3-2 and increase the Position Accuracy 1 3-4, which is used to compute the Mobile Device Absolute Position 1-2. For example, the first Position Data 1 3-2 may be a first estimate of the Mobile Device Absolute Position using GPS, with a first Position Accuracy 1 3-4, the second Position Data 2 3-3 may be a GPS correction message computed by an Assisted GPS Server taking advantage of a known location of a Cell Tower. The second Position Data 2 3-3 is used to correct the first Position Data 1 3-2 and compute the Mobile Device Absolute Position 1-2 with increased accuracy. In a third example, the Hybrid Positioning System 3-1 uses the first Position Data 1 3-2 to compute the Mobile Device Absolute Position 1-2 in certain conditions and the second Position Data 2 3-3 to compute the Mobile Device Absolute Position 1-2 in other conditions. For example, the first Position Data 1 3-2 may be an estimate of the Mobile. Device Absolute Position using GPS, which is used to compute the Mobile Device Absolute Position 1-2 when the Mobile Device 1-1 is outdoor and without obstructions on the line of sight to the GPS satellites, which are the conditions in which GPS measurements are most accurate. The second Position Data 2 3-3 may be an estimate of the Mobile Device Absolute Position using Cell Tower or Wi-Fi triangulation, which is used to compute the Mobile Device Absolute Position 1-2 when the Mobile Device 1-1 is indoor or in conditions were the GPS measurement is inaccurate or not even possible.
A Mobile Device 1-1 such as a cellphone, a smartphone, a tablet, or a wearable device is illustrated in FIG. 4. The Mobile Device 1-1 consists of Hardware 4-1 and Software 4-2. The Hardware 4-1 comprises at least one Processor 4-3 and at least one Memory 4-4, The Hardware 4-1 also provides the user of the Mobile Device 1-1 with at least one mode of input and one mode of output. A first mode of input may consist of a Keypad 4-4, a first mode of output consist of a Screen 4-5. The Screen 4-5 may be a touch-sensitive screen, which provides a second mode of input Other modes of input and output, such as voice recognition, may also be provided (not shown). The Hardware 4-1 may also include a Camera 4-6, with which the user can take photos or videos using the Mobile Device 1-1. The Hardware 4-1 also provides Communication Links 4-7. A first communication link in the Communication Links 4-7 is a Cellular Radio 4-11, which includes a transmitter and a receiver, which connects the Mobile Device 1-1 to the Cellular Network 2-12. The Communication Links 4-7 may also include a Wi-Fi Radio 4-10, which includes a transmitter and a receiver, and enables the Mobile Device 1-1 to connect to a Wi-Fi Hotspot. The Communication Links 4-7 may also include a GPS Receiver 2-4 capable of receiving GPS signals from GPS Satellites. If the GPS Receiver 2-4 is present, the Mobile Device 1-1 is capable of computing its position using GPS. The Communication Links 4-7 may also include an Assisted GPS Receiver 4-8, capable of receiving information from an Assisted GPS Server 2-11 connected to the Cellular Network or to the Internet 2-8. If the Assisted GPS Receiver 4-8 is present, the Mobile Device 1-1 is capable of computing its position using Assisted GPS. The Software 4-2 comprises an Operating System 4-12 and a plurality of Mobile Applications comprising Mobile Application 1 4-13, Mobile Application 2 4-14, to Mobile Application N 4-15. Each Mobile Application in the plurality of Mobile Applications may provide specific functionality to the Mobile Device 1-1. One or more Mobile Applications running on the Mobile Device 1-1 may provide ways to compute the Mobile Device Absolute Position 1-2 or the Mobile Device Relative Location 1-12 using different positioning mechanisms, including Hybrid Positioning System. One or more Mobile Applications running on the Mobile Device 1-1 may be Location-Based Mobile Applications and use the computed Mobile Device Absolute Position 1-2 or the Mobile Device Relative Position 1-12 in order to customize their functionality depending on the computed Mobile Device location.